ToneGenerator.h

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/****
 * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
 * Created 2015 by Skurydin Alexey
 * http://github.com/SmingHub/Sming
 * All files of the Sming Core are provided under the LGPL v3 license.
 *
 * ToneGenerator.h - Tone generation via I2S
 *
 * @author Sept 2019 mikee47 <mike@sillyhouse.net>
 *
 ****/

#pragma once

#include "ToneGenerator/ToneBufferQueue.h"
#include <WString.h>
#include <driver/i2s.h>

#define TG_VOICE_MAP(XX)                                                                                               \
    XX(Sine)                                                                                                           \
    XX(Triangular)                                                                                                     \
    XX(Sawtooth)                                                                                                       \
    XX(Square)

#define TG_EFFECT_MAP(XX)                                                                                              \
    XX(Normal)                                                                                                         \
    XX(Mute)                                                                                                           \
    XX(FadeIn)                                                                                                         \
    XX(FadeOut)

class ToneGenerator
{
public:
    enum class Voice {
#define XX(t) t,
        TG_VOICE_MAP(XX)
#undef XX
            MAX
    };

    enum class ToneEffect {
#define XX(t) t,
        TG_EFFECT_MAP(XX)
#undef XX
    };

    static String getVoiceName(Voice voice);
    static String getEffectName(ToneEffect effect);

    ~ToneGenerator()
    {
        end();
    }

    bool begin(unsigned sampleRate);

    void end();

    bool start();

    void stop();

    bool isStarted()
    {
        return started;
    }

    ToneBuffer* createTone(Voice voice, unsigned frequency, ToneEffect effect, unsigned repeatCount = 0);

    void queueTone(Voice voice, unsigned frequency);

    void submitPending()
    {
        transition.append(pending);
    }

private:
    ToneBuffer* allocateBuffer(unsigned sampleCount);
    int16_t getSampleValue(Voice voice, unsigned pos, unsigned sampleCount, int16_t amplitude);
    static void IRAM_ATTR i2sCallback(void* param, i2s_event_type_t event);
    void IRAM_ATTR i2sWrite();
    bool IRAM_ATTR i2sWriteBuffer(ToneBuffer* buffer, bool end);

private:
    unsigned sampleRate;
    unsigned curFreq = 0;
    static constexpr uint8_t fadeCycles = 2;
    static constexpr uint8_t noteGapMs = 16;
    // Three buffer queues
    ToneBuffer* active = nullptr;
    ToneBufferQueue pending;
    ToneBufferQueue transition;
    ToneBufferQueue unused;
    unsigned offset = 0; // Read position in active buffer
    bool started = false;
};